Friday, August 17, 2018

CCTV DVR sytem – further Q?

August 12, 2011 by admin  
Filed under CCTV DVR

How many days will the recording data kept for 750 Gmb? What is 2TB? How much is the prices’ difference?

1Tb = 1000 Gb. So 2 Tb is 2000 Gb, i.e. 2.5 times bigger.

The difference in hardware costs (bigger disk drive) is about £100.

You should avoid low end kit that claims ‘full resolution’ ‘16 channels’ .. one way they achieve this is to have 1 digitising channel that records one frame from each camera in turn .. so if you have 2 cameras ‘active’ it’s recording half the data from each (if you actually try to use such kit with 16 camera’s you will get 1/16th of each ). Other systems simply ‘chop up’ the frame – so they record one camera at 600×800 but fit 4 camera’s and you get only get 300×400 ’sub frame’ of each (so they fit all 4 into the 600×800 field) – needless to say, such a system with 16 camera’s will only be recording a tiny 150×200 ‘thumbnail’ view from each camera …

Things like positioning of camera’s etc. is not easy, since any intruder will look out for the obvious cameras and try to stay out of the field of view etc. – some installers will even fit obvious camera’s (eg over the door) so the dumb crook faces away and looks straight into the hidden camera built into the door ’spy eye’. You might want to go and see real system ‘in action’ before deciding how to proceed ..

Comments

2 Responses to “CCTV DVR sytem – further Q?”
  1. DEREK C says:

    750 Gmb is .75 Tb therefore 2Tb is approx 2.5 times the size.

    750 Gmb of recording time will depend on many factors, The quality of the recording and whether its recording all the time or just changes to the image. its complex
    References :

  2. Steve B says:

    1Tb = 1000 Gb. So 2 Tb is 2000 Gb, i.e. 2.5 times bigger.

    The difference in hardware costs (bigger disk drive) is about £100.

    However manufactures of such systems typically offer a ‘loss leader’ (low function, low capacity) bottom of the range system for a competitive price (so a basic 4 camera 750Gb system is likely to have a price under £500) whilst trying to make their profits on the ‘high end’ (= actually usable) system = so a 2Tb multi (digitising) channel DVR with 8 cameras is likley to have a price tag of £2,000 or more ..

    You should avoid low end kit that claims ‘full resolution’ ‘16 channels’ .. one way they achieve this is to have 1 digitising channel that records one frame from each camera in turn .. so if you have 2 cameras ‘active’ it’s recording half the data from each (if you actually try to use such kit with 16 camera’s you will get 1/16th of each ). Other systems simply ‘chop up’ the frame – so they record one camera at 600×800 but fit 4 camera’s and you get only get 300×400 ’sub frame’ of each (so they fit all 4 into the 600×800 field) – needless to say, such a system with 16 camera’s will only be recording a tiny 150×200 ‘thumbnail’ view from each camera …

    You either learn about it yourself (try Google) or you get a commercial company to quote (expect to pay double the ‘headline’ prices for the kit and double again for installation – i.e. a ‘reasonable’ £2k commercial system will cost you about £10k including installation)

    Things like positioning of camera’s etc. is not easy, since any intruder will look out for the obvious cameras and try to stay out of the field of view etc. – some installers will even fit obvious camera’s (eg over the door) so the dumb crook faces away and looks straight into the hidden camera built into the door ’spy eye’. You might want to go and see real system ‘in action’ before deciding how to proceed ..

    You also have to be aware that the basic cameras supplied with most kits have a realistic range of a few yards (especially at night in IR mode) and (despite the hype) limited resolution ESPECIALLY as many systems ‘exaggerate’ their recording time by dropping the resolution and over-compressing .. so before parting with any money you should demand to see actual footage taken with any proposed CCTV camera system ..
    References :

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